1. Field of the Invention
The present invention relates to an input buffer for a semiconductor device, and more particularly to an input device for a semiconductor device which can improve the performance characteristic of the semiconductor device by applying OCD (Off-Chip Driver) information to the input buffer.
2. Description of the Prior Art
As generally known in the art, the performance of a semiconductor device may deteriorate due to skew that occurs in the fabricating process of the semiconductor device. This performance deterioration due to the skew becomes severer as the integration and speed of a semiconductor device increase.
In order to prevent the performance deterioration of an interface unit due to the skew, a conventional semiconductor device applies OCD (Off-Chip Driver) information to an output driver.
The OCD information means information about an impedance value of the output driver of the semiconductor device.
The OCD information will be explained in more detail.
Generally, the output driver of the semiconductor device does not have a constant output impedance value due to the skew phenomenon caused by variation of processing parameters. Accordingly, a designer of the semiconductor device checks the variation of the output impedance of the output driver and controls the checked output impedance of the output driver so that the output impedance matches an input impedance of an external system. Information about the performance characteristics of the output driver obtained by the above-described impedance matching is the OCD information. In other words, the OCD information includes information about the skew of the semiconductor device.
According to the related art, if the impedance characteristic of the output driver of the semiconductor device is changed due to the skew occurring in the fabricating process of the semiconductor device, the impedance of the output driver is adjusted using the OCD information as described above. However, any apparatus for adjusting the skew of the input device by applying the OCD information to the input device of the semiconductor device has not been proposed.
As shown in FIG. 1, a conventional input device of a semiconductor device typically includes an ESD (Electro-Static Discharge) circuit 100, a receiver 110, a setup-hold delay unit 120 and a latch 130. In FIG. 1, the input device has no construction for correcting the skew.
Accordingly, if the performance characteristic of the input device of the semiconductor device is changed due to the skew occurring in the fabricating process of the semiconductor device as shown in FIG. 1, the input signal changed by the skew affects the semiconductor device as it is.
Consequently, the performance characteristic of the semiconductor device deteriorates due to the skew, and this performance deterioration due to the skew becomes more severe in the case of a high-speed semiconductor device.